Biochemical studies of cardiovascular connective tissue macromolecules are being conducted on clinical and experimental models. The carbohydrate-protein macromolecules like acid mucopolysaccharides (MPS), proteoglycans, glycoproteins, and MPS-lipoprotein interaction are being observed. Studies of proteoglycan(s) extracted from bovine aorta by dissociative techniques have resulted in the isolation of a homogeneous material with a sedimentation coefficient of S20 sub 0 3.2, an approximate molecular weight of 70,000. The proteoglycan obtained from the aorta is a copolymer containing chondroitin sulfates A and C, and dermatan sulfate and might be considered a basic unit which aggregates in the presence of a link protein and hyaluronic acid. Since other MPS are known to be present in the arterial wall and have not been obtained by these extraction methods, further studies are being conducted to isolate those MPS in their protein-bound state. At present, little is known of the proteoglycans from blood vessels, and one objective of these studies is to improve the methods for their isolation. An easy, rapid method for quantitating serum lipoproteins has been developed and is being used for several programs. Studies of 93 patients undergoing coronary artery angiography indicated a relationship of the concentration of beta-lipoprotein to abnormal vessel changes not observed with serum cholesterol or triglycerides. The same method is being applied to nutritional studies with subhuman primates and is quite helpful in following the course and response of serum lipoproteins. Phylogenetic studies have indicated great differences in Old and New World monkeys and in serum lipoprotein profiles. Marked intra as well as inter species differences in serum lipoprotein responses have been observed. Studies of the interaction between serum lipoproteins and MPS indicate a significant influence on the insoluble complex formation by the cations, Ca ion, Mg ion, and Mn ion.